Relationship between wadi drainage characteristics and peak-flood flows in arid northern Oman

Relationships between watershed characteristics and mean wadi flood peaks in arid regions are investigated. Mean flood peak discharge was derived for 12 watersheds ranging from 64 to 1730 km(2) in Oman using 270 flood events from 10 years of record. Fourteen watershed characteristics were automatically extracted from a digital elevation model, and multiple regression was used to investigate the effect of these characteristics on wadi mean peak flow (QMPF) and 5-, 10-, 20-, 50- and 100-year return period flood peaks. Drainage area (DA), wadi slope (WS), watershed mean elevation (BE) and agricultural/farm area (FR) were found to be the key variables affecting flood flows. As return period increased, the influence of BE on flood-peak estimation decreased. In addition, urbanization is increasing alongside increasing agricultural areas, and the inclusion of FR in the relationship improved the variance explanation by 11% over models using only traditional variables such as DA and BE.